目的　通过研究中国汉族人群δ氨基 γ 酮戊酸脱水酶 (ALAD)基因型 ,探讨中国儿童是否存在ALAD基因的遗传多态性及其频率分布特点 ,以确定遗传因素对儿童血铅水平的影响。方法　整群抽取对铅毒性较为敏感的 6～ 10岁儿童 2 2 9名为研究对象。通过PCR及限制性内切酶酶切分析两种ALAD等位基因的频率。结果　所研究儿童中ALAD 1 1型有 2 11例 ,ALAD 1 2型有 18例。ALAD2 基因频率为 8% ;ALAD1基因频率为92 %。未发现ALAD 2 2型。结论　中国人ALAD基因存在遗传多态性 ;从遗传特质上来说 ,中国儿童对铅毒性的易感性可能低于欧美儿童。

Objective To explore the genetic polymorphism of the δ aminolevulinate dehydratase (ALAD) gene in children of the Han ethnic group. Methods The erythrocyte σ aminolevulinate dehydratase (ALAD) isozyme phenotypes were determined in a population of 229 pre school and primary school children aged 6～10 years. Results (1) There were 211 individuals with the ALAD 1 1 isozyme phenotype and 18 individuals with the ALAD 1 2 isozyme phenotype. (2) The phenotype of ALAD 2 2 was not detected. Conclusions A polymorphic enzyme exists in the ALAD gene of the Chinese population and the ALAD 2 allele frequency was lower than in Caucasians. Chinese children are genetically less susceptible to lead toxicity than Caucasian children. [